diff --git a/Gemfile b/Gemfile
index 0cec73e8a..e5d12b076 100644
--- a/Gemfile
+++ b/Gemfile
@@ -38,6 +38,7 @@ gem 'diff-lcs', :require => "diff/lcs/array"
 gem 'bcrypt-ruby', :require => "bcrypt"
 gem 'aws-s3', :require => "aws/s3"
 gem 'awesome_print'
+gem 'statistics2'
 
 group :production do
   gem 'unicorn', :platforms => :ruby
diff --git a/Gemfile.lock b/Gemfile.lock
index 4251a77e0..8bb1a6f2d 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -179,6 +179,7 @@ GEM
       multi_json (~> 1.0)
       rack (~> 1.0)
       tilt (~> 1.1, != 1.3.0)
+    statistics2 (0.54)
     term-ansicolor (1.1.4)
     therubyracer (0.11.4)
       libv8 (~> 3.11.8.12)
@@ -241,6 +242,7 @@ DEPENDENCIES
   shoulda
   simple_form
   simplecov
+  statistics2
   term-ansicolor
   therubyracer
   timecop
diff --git a/app/controllers/reports_controller.rb b/app/controllers/reports_controller.rb
new file mode 100644
index 000000000..571332e66
--- /dev/null
+++ b/app/controllers/reports_controller.rb
@@ -0,0 +1,7 @@
+class ReportsController < ApplicationController
+  before_filter :janitor_only
+
+  def user_promotions
+    @report = Reports::UserPromotions.new
+  end
+end
diff --git a/app/logical/reports/user_promotions.rb b/app/logical/reports/user_promotions.rb
new file mode 100644
index 000000000..1ce13e8f1
--- /dev/null
+++ b/app/logical/reports/user_promotions.rb
@@ -0,0 +1,29 @@
+require 'statistics2'
+
+module Reports
+  class UserPromotions
+    def self.confidence_interval_for(user, n)
+      up_votes = Post.where("created_at >= ?", min_time).where(:uploader_id => user.id).where("fav_count >= ?", n).count
+      total_votes = Post.where("created_at >= ?", min_time).where(:uploader_id => user.id).count
+      ci_lower_bound(up_votes, total_votes, 0.95)
+    end
+
+    def self.ci_lower_bound(pos, n, confidence)
+      if n == 0
+        return 0
+      end
+
+      z = Statistics2.pnormaldist(1-(1-confidence)/2)
+      phat = 1.0*pos/n
+      100 * (phat + z*z/(2*n) - z * Math.sqrt((phat*(1-phat)+z*z/(4*n))/n))/(1+z*z/n)
+    end
+
+    def self.min_time
+      30.days.ago
+    end
+
+    def users
+      User.joins(:posts).where("users.level < ?", User::Levels::CONTRIBUTOR).where("posts.created_at >= ? and posts.fav_count >= 1", self.class.min_time).order("users.name")
+    end
+  end
+end
diff --git a/app/views/reports/user_promotions.html.erb b/app/views/reports/user_promotions.html.erb
new file mode 100644
index 000000000..ae0364aeb
--- /dev/null
+++ b/app/views/reports/user_promotions.html.erb
@@ -0,0 +1,30 @@
+<div id="c-reports">
+  <div id="a-user-promotions">
+    <h1>User Promotion Confidence Intervals</h1>
+
+    <p>Binomial proportion confidence interval for how likely a user's uploads will achieve a fav count of at at least n with 95% confidence within the past 30 days.</p>
+
+    <table width="100%" class="striped">
+      <thead>
+        <tr>
+          <th>User</th>
+          <th>Level</th>
+          <th>score:1+</th>
+          <th>score:5+</th>
+          <th>score:10+</th>
+        </tr>
+      </thead>
+      <tbody>
+        <% @report.users.each do |user| %>
+          <tr>
+            <td><%= link_to user.name, user_path(user) %></td>
+            <td><%= user.level_string %></td>
+            <td><%= number_to_percentage Reports::UserPromotions.confidence_interval_for(user, 1), :precision => 0 %></td>
+            <td><%= number_to_percentage Reports::UserPromotions.confidence_interval_for(user, 5), :precision => 0 %></td>
+            <td><%= number_to_percentage Reports::UserPromotions.confidence_interval_for(user, 10), :precision => 0 %></td>
+          </tr>
+        <% end %>
+      </tbody>
+    </table>
+  </div>
+</div>
\ No newline at end of file
diff --git a/app/views/static/site_map.html.erb b/app/views/static/site_map.html.erb
index b5ab87bbb..626befd5c 100644
--- a/app/views/static/site_map.html.erb
+++ b/app/views/static/site_map.html.erb
@@ -55,6 +55,12 @@
         <li><%= link_to("Listing", pools_path) %></li>
         <li><%= link_to("Changes", pool_versions_path) %></li>
       </ul>
+      <% if CurrentUser.user.is_janitor? %>
+        <ul>
+          <li><h1>Reports</h1></li>
+          <li><%= link_to("User Promotions", reports_user_promotions_path) %></li>
+        </ul>
+      <% end %>
     </section>
     <section>
       <ul>
diff --git a/app/views/users/index.html.erb b/app/views/users/index.html.erb
index 0fdcfdf55..aa6d5584a 100644
--- a/app/views/users/index.html.erb
+++ b/app/views/users/index.html.erb
@@ -14,8 +14,10 @@
           <th>Name</th>
           <th>Posts</th>
           <th>Deleted</th>
-          <th>% Pos</th>
-          <th>% Neg</th>
+          <% if CurrentUser.user.is_janitor? %>
+            <th><abbr title="1+ Favorite(s) Binonimial Confidence Interval">1+ FBCI</abbr></th>
+            <th><abbr title="5+ Favorites Binonimial Confidence Interval">5+ FBCI</abbr></th>
+          <% end %>
           <th>Notes</th>
           <th>Level</th>
           <th>Joined</th>
@@ -37,12 +39,9 @@
             </td>
             <td><%= link_to user.posts.count, posts_path(:tags => "user:#{user.name}") %></td>
             <td><%= user.posts.deleted.count %></td>
-            <% if user.posts.count > 100 %>
-              <td><%= number_to_percentage(100 * user.posts.positive.count.to_f / user.posts.count, :precision => 0) %></td>
-              <td><%= number_to_percentage(100 * user.posts.negative.count.to_f / user.posts.count, :precision => 0) %></td>
-            <% else %>
-              <td></td>
-              <td></td>
+            <% if CurrentUser.user.is_janitor? %>
+              <td><%= number_to_percentage Reports::UserPromotions.confidence_interval_for(user, 1), :precision => 0 %></td>
+              <td><%= number_to_percentage Reports::UserPromotions.confidence_interval_for(user, 5), :precision => 0 %></td>
             <% end %>
             <td><%= link_to user.note_versions.count, note_versions_path(:search => {:updater_id => user.id}) %></td>
             <td><%= user.level_string %></td>
diff --git a/config/routes.rb b/config/routes.rb
index 1a8d1a1ca..86c1ba663 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -167,6 +167,7 @@ Danbooru::Application.routes.draw do
     end
   end
   resource :related_tag, :only => [:show]
+  match "reports/user_promotions" => "reports#user_promotions"
   resource :session do
     collection do
       get :sign_out